In semiconductor production, the Standard Mechanical Interface (SMIF) is a typical handling system to assure wafers or photomasks are contained in a low-particle environment where contamination has little chance to occur, since wafers under production are vulnerable to airborne particles, particularly in nanoscale copper processes. Thus, SMIF pods are commonly used in the production line for carrying wafers. In addition, the Front Opening Unified Pod (FOUP) is a standard container for handling large wafers—300 mm or 450 mm in diameter, for example. Both SMIF pods and FOUP containers provide high level of clean-room environment to the wafers or photomasks, avoiding potential damage due to particle contamination during handling and storage.
According to current practice, clean gas such as pure nitrogen or clean dry air (CDA) is purged into wafer or photomask containers to maintain cleanliness, while humidity change inside the containers is considered an indicator for the cleanliness inside the containers. To maintain the cleanliness inside the SMIF pods and FOUP containers, there is a need to enhance the air-tight effect of the containers on the one hand, and to reduce the processing time for purging the container on the other hand. However, the purging process for traditional FOUP containers takes time, since there are only limited number of air-exhausting elements disposed on the housing of each FOUP container, and there is no other exit for the gas inside the containers to be exhausted. When the FOUP door is to be opened, it takes time and efforts to move the door off the FOUP container under air-tight condition, since the air-tight element disposed on the door retards the process of pressure balance inside and outside the container.
In order to overcome these drawbacks in the prior art, a novel design of containers for carrying wafers or photomasks is provided. The novel design of the present invention not only solves the problems described above, but also is easy to implement. Thus, the present invention has the utility for the industry.